This application is based on Japanese Patent Application HEI 11-89366, filed on Mar. 30, 1999, the entire contents of which are incorporated herein by reference.
a) Field of the Invention
This invention relates to an image-processing apparatus for an on-screen-display, which displays one image over another image.
b) Description of the Related Art
There is an electronic camera such as a digital still camera and a digital camcorder that have image sensors like CCDs. There is a technique called on-screen-display wherein image data output form the electronic camera are displayed onto a display device as a main image together with another image, e.g., text image, in a smaller size.
FIG. 8 shows an example of the on-screen-display. A small still image 21 showing a letter xe2x80x9cAxe2x80x9d is displayed at the upper right corner of the display playing a movie 20 of a baseball player. A size of the still image 21 is smaller than that of a screen area of the display.
FIG. 9 shows an example of a structure of an on-screen-display device according to prior art. Video signals VS from a CCD or the like are inputted to a monitor (a display device) 30, and a picture according to the video signals VS is displayed on the monitor. The video signals VS correspond to the movie 20 of the baseball player in FIG. 8. Data for the on-screen-display, e.g., font data FD corresponding to the text image 21 of the letter xe2x80x9cAxe2x80x9d in FIG. 8, are inputted to a microcomputer 31.
The microcomputer 31 calculates the position and area of a screen where the text image 21 will be inserted based on synchronizing signals SS of the video signals VS. The microcomputer 31 counts the synchronizing signals SS up until the calculated position of the text image 21 and outputs a keying signal KY to a selector 33. Then the microcomputer 31 outputs color data, instead of the video signals of the movie of the baseball player, to the monitor 30 via the selector 33 for a pixel at a time. The color data contain color information of the letter xe2x80x9cAxe2x80x9d and its background of the text image 21 that are picked up from a color palette 32 on the basis of the font data. For example, the color palette 32 may be able to produce 256 colors.
The on-screen-display according to the prior art can only display a text image as an image displayed on the screen, and colors for the image displayed on the screen are limited to artificial primary colors produced by the color palette. Therefore, its capability of color expression is limited. Also, original video data is overwritten by text image data, and therefore the image data cannot be moved anywhere, and the image size cannot be changed.
It is an object of this invention to provide an image processing apparatus that can freely display onto an on-screen-display not only text information but also an image other than a text image and also a natural image including natural or transparent colors taken with a camera as a still or a motion picture.
According to one aspect of the present invention, there is provided an image processing apparatus comprising an image memory comprising a first storing area for storing first image data for a background and a second storing area for storing second image data for an on-screen-display; a display buffer memory for storing data in a format used for display based on said first and second image data read from said image memory; and a controller for controlling accesses to said image memory and said display buffer memory, the controller reading the first image data from said first storing area in said image memory and writing said first image data into said display buffer memory and reading the second image data from said second storing area in said image memory and writing said second image data into a designated area in said display buffer memory.
The first image data for a background and the second image data for on-screen-display are stored separately in the image memory. The first image data is read from the image memory and written in the display buffer memory, and then the second image data is read from the image memory and written in the display buffer memory. Not only the text image but also natural images can be used for an on-screen-display, and those images can be displayed in any sizes and at any positions on the screen. Also, those images can be moved afterward and colored in transparent colors or composite colors.